Wind rose?

rachel younghans

Posted 22 September 2010 - 04:23 PM

rachel younghans

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So in Lopo Homem's World Map there are all these kind of faint diagonals in the background..... some coming from roses and some coming from unmarked centers. What do these represent? What about the roses, located mostly in the seas and around the periphery of the map? Are those windroses?

Hans van der Maarel

Posted 23 September 2010 - 12:05 AM

Hans van der Maarel

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So in Lopo Homem's World Map there are all these kind of faint diagonals in the background..... some coming from roses and some coming from unmarked centers. What do these represent? What about the roses, located mostly in the seas and around the periphery of the map? Are those windroses?

Wind or compass roses they're called, if I recall correctly. Along with the lines they're used to determine compass headings. Using those, a ship can navigate its way around.

Posted 23 September 2010 - 02:40 AM

The straight lines criss-crossing many portolan charts represent the thirty-two directions (or headings) of the mariner's compass from a given point. This is similar to the compass rose displayed on later maps and charts. Naming or demonstrating all thirty-two points is called boxing the compass.